Automatic sheet-feeding scanning apparatuses are widely used to scan images of documents because they can scan many documents at a time. Generally, a typical automatic sheet-feeding scanning apparatus principally includes an automatic paper feeder and a flatbed scanner. The automatic paper feeder is mounted on a glass platform of the sheet-feeding scanner. This automatic sheet-feeding scanning apparatus is capable of scanning a single document in a flatbed scanning mode by placing the document on the glass platform. Alternatively, this automatic sheet-feeding scanning apparatus is capable of successively scanning many documents in a sheet-feeding scanning mode.
Referring to FIG. 1(a), a schematic perspective view of a conventional automatic sheet-feeding scanning apparatus is illustrated. The automatic sheet-feeding scanning apparatus 100 of FIG. 1(a) principally includes a flatbed scanner 101, a glass platform 102, a scanning window 103 for performing a sheet-feeding scanning operation and a rib structure 104. The rib structure 104 is arranged at a side of the scanning window 103 for guiding the document transported by the automatic paper feeder (not shown) to pass through the scanning window 103 so as to implement the sheet-feeding scanning operation.
The automatic sheet-feeding scanning apparatus 100, however, still has some drawbacks. For example, in a case that a document P (e.g. a map) having a size greater than the glass platform 102 is placed on the glass platform 102, the rib structure 104 is covered by the document P. For performing a flatbed scanning operation, the automatic paper feeder (not shown) which corresponds to the upper cover of the automatic sheet-feeding scanning apparatus 100 needs to be laid on the glass platform 102. During the automatic paper feeder is laid on the glass platform 102, a downward force is exerted on the document P. Since the rib structure 104 is a salient, the rib structure 104 may pierce through the document P under action of the downward force. Referring to FIG. 1(b), the rib structure 104 causes damage of the document P.
Therefore, there is a need of providing an improved automatic sheet-feeding scanning apparatus to overcome the above-described disadvantages.